I had a mock interview with a young undergraduate student with ICPC contest experience. So I like to ask him to solve my favorite algorithm Array quadruplet. I think that he did one on dynamic programming, and then I tried to evaluate how good he is.
Biggest surprise was that he gave me the solution I could not understand. And then I asked him a few question, ask him to explain using example. He did perfect job to explain the algorithm.
It turned out the algorithm is optimal solution. I like to post the answer for my own question asked more than 6 months ago. Here is my question link.
Here is the algorithm the peer wrote. At the end of interview, I asked him to connect to linkedin, it turned out that he worked for facebook as an intern already.
I could not believe that my mock interview practice was so many surprise and I just enjoyed the talk. Somehow I complained to the peer that I do not want to study so many system design interview, I do not want to try to memorize so many things, I like to work on the algorithm with the peer on mock interview instead.
We met and talked about one hour fifty minutes until the mock interview terminated the discussion. I could not believe that I enjoyed the discussion of the algorithm so much, I never expected that I will meet a super talent later in Saturday evening.
Feedback from the peer
You just do as you do in the mock interview practice session, you should be able to do fine in any interview. That is my advice.